JPH10332413A - Method for establishing sattelite navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To support the radio position determination by a user in cooperation with other systems by using the connection between the moving-body communica tion network, which is arranged at an LEO (low orbit) or at MEO (middle orbit) located lower than the stationary orbit of the earth, and the communica tion seattelite on the stationary orbit. SOLUTION: A plurality of satellites surrounding the earth on many near- polar orbits are directly linked and connected a central satellite 4 in the group constituted of e.g. the satellite 4 to a satellite 20 by an optical communication linking means. Furthermore, the transmission of the information is performed through the entire network by the transfer of the information between the network-constituting elements formed of the satellite 4 to the satellite 20. At this time, the measurement of the delay time and the arranging accuracy of the optical means utilize for the optical communication link between the satellites are used for determining the mutually accurate relative positions of the satellites. Furthermore, the time standard, which is executed in mounting on the satellite, is calibrated by the optical means through the communication between the satellites.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth orbit below a geosynchronous orbit, in particular, LEO (low orbit) or ME.
Using a mobile communication satellite network located in O (middle orbit) and a connection to a communication satellite in geosynchronous orbit to establish a satellite navigation system (navigation system or navigation support system). About the method.

[0002]

BACKGROUND OF THE INVENTION For example, GPS (American Global Positioning System), GLONASS (Russian system) or planned European system (G
Conventional satellite navigation systems, such as the NSS (Global Satellite Navigation System), are implemented or planned using methods for specially positioning several satellites orbiting the earth in polar or geosynchronous orbit. ing. For example, the GNSS planned in Europe can be realized by including satellites of the INMARSAT (Inmarsat: International Maritime Satellite Organization) network moving in geosynchronous orbit. GPS satellites move in polar orbit at an altitude of about 20,000 km and transmit radio signals at one or two frequencies ranging between 1 GHz and 2 GHz, depending on the user, where the ultra wideband An accurate time marker is transmitted to a terrestrial user by means of a permanently repeating modulation with a long data sequence. Because of the ultra-wideband modulated signal and its relatively low repetition rate, the spectrum of these radio signals gives the effect of white noise close to their respective center frequencies. Since the phase of the radio signal is modulated, negative modulation using the same modulation signal can cause it to return to the unmodulated state at the receiver, and the same modulation signal, due to its special structure , And can be detected almost without noise by an ultra-narrow band filter.

The synchronization of the second modulation process at the receiver, which is necessary for this, makes it possible to determine the difference in distances at which the instantaneous positions are simultaneously received from several satellites whose known positions are known. . Also from this, the position of the user is accurately determined as in the case of the hyperbolic navigation.

[0004] By operating at two different frequencies,
Compensation for the ionospheric properties surrounding the earth is made for a group of users with suitable equipment. Here, the structure of the ionospheric characteristics changes every sunspot period, season, and day, which extend over a period of about 11 years (see, for example, Prior Art Document 1 “Lambert
Lambert Wanninger, "Effects of the ionosphere on GPS positioning (Der Einfluss der lon)
osphare auf die Positionerung mit GPS) ", Hannover University, 1994 ISSN0174
-1454).

In addition, the use of commercial receivers has been hindered by errors that are deliberately generated by US Air Force operators, for example, to determine gun positions quickly and easily. Thus, all other similar conventional and planned systems that use high-Earth orbit satellites will break market monopolies with a single system and have a globally high profile regardless of non-essential political and military situations. Its primary purpose is to make available position determination with accuracy.

[0006]

The above systems do not work cooperatively and there is no two-way link connection between the satellite and the individual users of the system. Thus, the number of users is infinite and out of control due to the full operation of the system. The good visibility capability established by each satellite's high orbit allows the number of satellites covering the entire earth's surface to be kept low. 21 for GPS
One working satellite is sufficient. However, it is almost impossible to selectively cancel the use of the system in a limited small area of the globe and avoid integration into military systems. Furthermore, in the case of a system that assumes joint position determination using satellites located in relatively high orbits to control unnecessary use, the number of allowed users is only a small number given the conventional lack of frequency. It is slight.

It is an object of the present invention to solve the above problems, to be able to cooperate with other systems, to provide a bidirectional link connection between the satellite and the individual users of the system, It is an object of the present invention to provide a method for establishing a satellite navigation system capable of assisting a user of a LEO and / or MEO communication system in determining a radio position.

[0008]

SUMMARY OF THE INVENTION According to the present invention, it is an object of the present invention that several linked satellites communicating using an optical information link are utilized for navigation assistance or navigation. Achieved by the characteristic functions of

A method for establishing a satellite navigation system according to the present invention is a mobile communication satellite located in an LEO (low orbit) or MEO (medium orbit) located below a geosynchronous orbit of the earth. A method for establishing a satellite navigation system using a network and a connection with a communication satellite in geosynchronous orbit, wherein a plurality of link-connected satellites communicating by an optical communication link are used for navigation. It is characterized by having been done.

In the above method for establishing a satellite navigation system, preferably, the delay time measurement and the alignment accuracy of the optical means used for the optical communication link between the satellites are accurate relative to each other. Used for position determination. Further, in the above method for establishing a satellite navigation system, preferably the time standard executed onboard the satellite is calibrated by optical means via inter-satellite communication. Still further, in the method for establishing a satellite navigation system,
Preferably, in systems with multiple satellites in low orbit, a non-cooperative method is used which is more useful with geographic selection methods.

In the method for establishing a satellite navigation system, preferably, the signal transmitted by the user or the characteristic detectable as a time marker of the signal transmitted by the user is received by a plurality of satellites. , Coupled by an optical communication link between the satellites and fed to one satellite to determine the position of the user by a cooperative positioning method. Further, in the method for establishing a satellite navigation system, the optical communication link with the geosynchronous orbit satellite is used to more accurately determine the position of the satellite operating cooperatively or non-cooperatively with the user. You. Still further, in the method for establishing a satellite navigation system, the position of the satellite operating cooperatively or non-cooperatively with the user is determined by the existing navigation system.

Also, in the method for establishing a satellite navigation system, preferably, the time standard and the frequency standard of the existing navigation system include a user's collaborative or non-cooperative position determination on the system's satellites. And / or used to calibrate on-board time and frequency standards. Further, in the method for establishing a satellite navigation system, the non-cooperative positioning of the satellite by the system in low orbit or medium orbit is performed by using a calibrated signal of the satellite passing through the user's coverage area at a different orbit at high speed. This is done by observing the Doppler frequency shift by the user.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a configuration of a TELEDESIC network which is a low-orbit satellite network according to an embodiment of the present invention. FIG. 2 is a diagram showing a link connection by direct optical connection in the embodiment. TE
FIG. 2 is a perspective view illustrating an LEDESIC network group.

FIG. 1 shows an example of a satellite communication network (TELEDESIC project) composed of 840 satellites 2 orbiting the earth in a number of near polar orbits. In this case, the plurality of satellites 2 are directly linked by optical communication link means to the central satellite 4 in the group consisting of satellites 4 to 20 shown in FIG. For example, the transmission of information
This is done over the entire network by transmitting information between network components consisting of several satellites 4 to 20 shown in FIG.

FIG. 3 is a perspective view and a plan view showing a satellite visibility area for a terrestrial user in the present embodiment. In the area 28 shown by the two detail views of FIG. 3, a terrestrial user can communicate with a satellite 26 orbiting the earth. The grid 30 extends to the area 28 in the right part of FIG. 3 and demonstrates that one satellite can reach several cells of the wireless network. On the other hand, a user in such a cell can always see several satellites, each of which individually functions as multiple cells of the network, with directional antennas or special multiplexing. I have. In general, it is possible to use a simultaneous connection with several satellites with which communication is possible for a navigation system.

FIG. 4 is a perspective view showing the coverage of one user in a satellite communication network cell covered by several consecutive satellites of the network of the present embodiment. Here, FIG. 4 shows radiation 4 in different directions.
0, 42, 44 indicate the simultaneous coverage of a user located in cell 32 by satellites 34, 36, and 38 moving continuously in orbit. However, it is also possible to cover a plurality of satellites respectively traveling in different orbits. The satellites 34, 36 and 38 all send signals with time markers to the user, similar to non-cooperative positioning systems such as GPS and GLONASS, and the user can independently determine the delay difference depending on each position. Perform arithmetic processing. Conversely, a user of the cooperative method arrives at satellites 34, 36 and 38 at different times and is coupled by an optical communication link between satellites 34, 36 and 38 to provide a known inter-satellite delay by measurement. The signal can be retained to obtain a position dependent delay difference analyzed using time. In this case, the user does not need special equipment. In addition, the network that can be used for position determination can be a part of a satellite located at a medium altitude on the earth or a satellite that orbits in a geosynchronous orbit. In addition, the satellites of the system can be assisted by non-cooperative use of existing navigation systems to assist the user in cooperative positioning.

As described above, according to the embodiment of the present invention, the basic concept of the present invention is to include a conventional inter-satellite communication link which is already well known. LEO (low orbit) or MEO (medium orbit) satellite communication networks and satellites in proximity networks have a limited field of view, so these networks are necessary. However, on the other hand, the limited visibility divides the part of the earth's surface covered by the system into a number of small cells, where sophisticated antennas are installed on the system's many satellites. No need. The non-fixed free distance between the satellite and the user is relatively short, allowing the use of terminals with low radiation output. With a close sequence of satellites in a large number of low orbits, each user can communicate with several satellites simultaneously and determine their position as in the case of GPS. In this case, a high-precision time standard mounted on a satellite can be averaged through a communication link between the satellites of the system, and therefore requires less than a GPS. When an optical communication link between satellites is used, it is possible to accurately determine the direction of the satellite operating as the opposite station in addition to the accurate position determination. By knowing the mutual positional relationship between the satellites by this method, the user can determine the position more accurately. Given the positional relationship between the satellites used by the user, providing the signal transmitted by the user or characteristics extracted from the signal to a central location using a known delay after its reception by some satellites. Is also possible. Here, the calculation of the position of the user is performed. In addition, the use of an optical communication link with geosynchronous orbit satellites expands the measurement base and thus increases the accuracy. It is also possible to use satellites orbiting in middle orbit or geosynchronous orbit to achieve a navigation system that operates cooperatively or non-cooperatively according to the method according to the invention.

Compared to the prior art, the advantages of the disclosed system according to the invention have the advantage that the inter-comparison of the time standards performed between the satellites and the mutual determination of the positional relationships by all the satellites involved in the system are possible. That is what. For this reason,
The determination of the trajectory-related data becomes more accurate and the accuracy of the non-cooperative positioning method increases.

A further advantage of the basic principle lies in the possibility of employing a cooperative positioning method. In this case, one user of the satellite-supported mobile radio network can convert the signal transmitted by the user to its own position by means of delay-time-supported processing, without having special equipment for position determination. There is an advantage that can be determined. The signal is transmitted by the user, and the satellites linked together receive it and are collected by the optical communication link. The advantage of this satellite navigation system, which consists of a plurality of satellites located in low orbit and can only be realized with the concept of the present invention, is that the potentially large number of users cooperatively determine their position, The ability to locally limit the use of cooperatively acting position determination methods.

[0021]

As described above in detail, according to the present invention, a satellite network for mobile communication arranged in LEO (low orbit) or MEO (medium orbit) located below the geosynchronous orbit of the earth. And a connection with a communication satellite in geosynchronous orbit, wherein a plurality of link-connected satellites communicating by an optical communication link are used for navigation. Is done. Also, in the method for establishing a satellite navigation system, preferably, a delay time measurement,
The alignment accuracy of the optical means used for the optical communication link between the satellites is used to determine the exact relative positions of the satellites. Further, in the above method for establishing a satellite navigation system, preferably the time standard executed onboard the satellite is calibrated by optical means via inter-satellite communication. Still further, in the method for establishing a satellite navigation system described above, preferably in a system having a plurality of satellites in a low orbit, a non-cooperative method that is more useful than a geographic selection method is used.

In the method for establishing a satellite navigation system, preferably, the signal transmitted by the user or the characteristic detectable as a time marker of the signal transmitted by the user is received by a plurality of satellites. , Coupled by an optical communication link between the satellites and fed to one satellite to determine the position of the user by a cooperative positioning method. Further, in the method for establishing a satellite navigation system, the optical communication link with the geosynchronous orbit satellite is used to more accurately determine the position of the satellite operating cooperatively or non-cooperatively with the user. You. Still further, in the method for establishing a satellite navigation system, the position of the satellite operating cooperatively or non-cooperatively with the user is determined by the existing navigation system.

[0023] Also, in the method for establishing a satellite navigation system, preferably, the time standard and the frequency standard of the existing navigation system include a user's collaborative or non-cooperative positioning with the system's satellites. And / or used to calibrate on-board time and frequency standards. Further, in the method for establishing a satellite navigation system, the non-cooperative positioning of the satellite by the system in low orbit or medium orbit is performed by using a calibrated signal of the satellite passing through the user's coverage area at a different orbit at high speed. This is done by observing the Doppler frequency shift by the user.

Thus, according to the present invention, the basic concept of the present invention consists in including the conventional inter-satellite communication links already known. LEO (low orbit) or MEO (medium orbit) satellite communication networks and satellites in proximity networks have a limited field of view, so these networks are necessary. However, on the other hand, the limited visibility divides the part of the earth's surface covered by the system into a number of small cells, where sophisticated antennas are installed on the system's many satellites. No need. The non-fixed free distance between the satellite and the user is relatively short, allowing the use of terminals with low radiation output. With a close sequence of satellites in a large number of low orbits, each user can communicate with several satellites simultaneously and determine their position as in the case of GPS. In this case, a high-precision time standard mounted on a satellite can be averaged through a communication link between the satellites of the system, and therefore requires less than a GPS. When an optical communication link between satellites is used, it is possible to accurately determine the direction of the satellite operating as the opposite station in addition to the accurate position determination. By knowing the mutual positional relationship between the satellites by this method, the user can determine the position more accurately. Given the positional relationship between the satellites used by the user, providing the signal transmitted by the user or the characteristics extracted from the signal to a central location using a known delay after its reception by several satellites. Is also possible. Here, the calculation of the position of the user is performed. In addition, the use of an optical communication link with geosynchronous orbit satellites expands the measurement base and thus increases the accuracy. It is also possible to use satellites orbiting in medium orbit or geosynchronous orbit to achieve a navigation system which operates cooperatively or non-cooperatively according to the method according to the invention.

The advantages of the system of the present disclosure as compared to the prior art are that the intercomparison of the time standards performed between the satellites and the mutual determination of the position relationships by all the satellites involved in the system is possible. That is what. For this reason,
The determination of the trajectory-related data becomes more accurate and the accuracy of the non-cooperative positioning method increases.

A further advantage of the basic principle lies in the possibility of employing a cooperative positioning method. In this case, one user of the satellite-supported mobile radio network can convert the signal transmitted by the user to its own position by means of delay-time-supported processing, without having special equipment for position determination. There is an advantage that can be determined. The signal is transmitted by the user, and the satellites linked together receive it and are collected by the optical communication link. The advantage of this satellite navigation system, which consists of a plurality of satellites located in low orbit and can only be realized with the concept of the present invention, is that the potentially large number of users cooperatively determine their position, The ability to locally limit the use of cooperatively acting position determination methods.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the configuration of a TELEDESIC network that is a low-orbit satellite network according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a TELEDESIC network group linked by direct optical connection in the embodiment.

FIGS. 3A and 3B are a perspective view and a plan view showing a visibility range of a satellite for a terrestrial user according to the embodiment; FIGS.

FIG. 4 is a perspective view showing a coverage area of one user in a satellite communication network cell covered by several consecutive satellites of the network of the embodiment.

[Explanation of symbols]

2,4,6,8,10,12,14,16,18,2
0, 26, 34, 36, 38 ... satellite, 22 ... orbit, 24 ... earth, 28 ... area, 30 ... grid, 32 ... cell, 40, 42, 44 ... radiation in different directions.

Claims (9)

[Claims] 1. L located below the earth's geosynchronous orbit
A method for establishing a satellite navigation system using a satellite network for mobile communications located in EO (low orbit) or MEO (medium orbit) and connections with communication satellites in geosynchronous orbit. A method for establishing a satellite navigation system, wherein a plurality of linked satellites communicating by an optical communication link are used for navigation. 2. The method according to claim 1, wherein the accuracy of the arrangement of the optical means used for the delay time measurement and for the optical communication link between the satellites is used for the determination of the exact relative position between the satellites. Item 3. A method for establishing a satellite navigation system according to item 1. 3. A method for establishing a satellite navigation system according to claim 1, wherein the time standard implemented on-board the satellite is calibrated by optical means via inter-satellite communication. . 4. A system having a plurality of satellites in low earth orbit, wherein a non-cooperative method is used which is made more useful by a geographical selection method. For establishing a satellite navigation system. 5. A signal transmitted by a user, or a property detectable as a time marker of a signal transmitted by a user, is received by a plurality of satellites and combined by an optical communication link between the satellites to form a single satellite. A method for establishing a satellite navigation system according to one of claims 1 to 4, characterized in that the position of the user is provided by means of a supplied collaborative position determination method. 6. An optical communication link with a geosynchronous orbit satellite used to more accurately determine the position of a satellite operating cooperatively or non-cooperatively with a user. A method for establishing a satellite navigation system according to one of claims 1 to 5. 7. The method according to claim 1, wherein the position of the satellite operating cooperatively or non-cooperatively with the user is determined by an existing navigation system.
A method for establishing a satellite navigation system according to any one of the preceding claims. 8. An existing navigation system time standard and frequency standard may be used to determine the user's collaborative or non-cooperative positioning and / or on-board time standard and frequency standard calibration on the system's satellites. Method for establishing a satellite navigation system according to one of the claims 1 to 7, characterized in that it is used for: 9. Non-cooperative positioning in a satellite-based system in low orbit or medium orbit, wherein the user observes the Doppler frequency shift of the calibrated signal of the satellite passing through the user's coverage at high speed in different orbits. Method for establishing a satellite navigation system according to one of the claims 1 to 8, characterized in that the method is performed by: